A typical such door hinge has a first housing and a second housing that can be fitted into recesses in the door frame and a narrow edge of the door panel, and a link assembly that connects the housings and has a least two links connected to one another pivotal at a vertical hinge pin. The link assembly is rotatable in the second housing in two separate inserts that are spaced apart from one another. These inserts are each adjustable relative to the second housing by a respective adjusting screw in a second horizontal direction perpendicular to a front face of the second housing.
The alignment of the vertical axis as well as the horizontal direction relates to the conventional installation situation of the door hinge.
Different configurations are known for concealed door hinges. Compared to door hinges with an exposed hinge knuckle, the advantage is produced that doors can be integrated optimally in planar wall surfaces without the door hinges being visible when the door is closed. As a result, the advantage is produced that when the door is closed the hinges are protected from environmental influences, damage or tampering. Furthermore, due to the form of the link assembly specially adapted pivoting sequences can be provided, in order also for example to be able to open doors with an offset. Finally, concealed door hinges frequently have an opening angle of 180°.
In order that the door panel can still be adjusted in the door frame even after installation, door hinges frequently have adjusting mechanisms for adjustment in three directions. The height of the door panel in the door frame can be adjusted by a height adjustment in the vertical direction. With a lateral adjustment in the horizontal direction parallel to the external surface of the door panel, the door panel can be moved laterally relative to its closed position inside the door frame. Finally, an adjustment of the door panel in the direction of its thickness is possible, which is designated as a compression adjustment. This designation derives from the fact that an adjustment in the direction of the thickness as a rule also determines the force with which a seal between the door panel and the door frame is compressed.
In order to make a lateral adjustment, ultimately the distance between the two housings must be changed relative to the closed position of the door panel. In this connection it is usual that one of the two housings has inserts supporting the link assembly for adjustment in the corresponding second horizontal direction. Generic configurations of door hinges to be recessed are known from U.S. Pat. Nos. 6,829,808, 8,196,265, U.S. 2010/0115729, U.S. Pat. Nos. 8,863,361 and 8,656,560.
According to the last-mentioned U.S. Pat. No. 8,656,560, a simple headed screw retained by a screw head in a seat in the associated insert can be used as an adjusting screw. This seat is then opened laterally in order to be able to introduce the adjusting screw easily during installation. The screw head is then retained by positive engagement in the adjustment direction. According to U.S. Pat. No. 8,656,560 it is not possible to avoid a certain movability of the adjusting screw inside the seat.